license: cc-by-4.0
pretty_name: GALAH DR4 — Stellar Abundances for 917k Stars
language:
- en
description: >-
The fourth data release of the Galactic Archaeology with HERMES survey —
radial velocities, stellar parameters, and up to 31 elemental abundances for
917,588 stars.
task_categories:
- tabular-classification
- tabular-regression
tags:
- space
- stars
- spectroscopy
- galah
- abundances
- astronomy
- open-data
- tabular-data
size_categories:
- 100K<n<1M
configs:
- config_name: default
data_files:
- split: train
path: data/galah_dr4_allstar.parquet
default: true
GALAH DR4 — Stellar Abundances for 917k Stars
Part of the Astronomy Datasets collection on Hugging Face.
The fourth data release of the GALactic Archaeology with HERMES (GALAH) survey, providing radial velocities, stellar parameters, and up to 31 elemental abundances for 917,588 stars observed with the HERMES spectrograph on the Anglo-Australian Telescope.
Dataset description
GALAH DR4 is one of the largest stellar spectroscopic surveys, designed to unravel the formation and evolution of the Milky Way through chemical tagging. Each star has high-resolution spectra decomposed into fundamental stellar parameters and individual elemental abundances spanning light elements, alpha-elements, iron-peak elements, and neutron-capture elements.
Key properties:
- 906,689 stars with radial velocity measurements
- 906,432 stars with at least one elemental abundance
- 30 elemental abundance columns ([X/Fe])
- Median 24 abundances per star
- Median SNR: 48.1 per pixel
Schema
| Column | Type | Description |
|---|---|---|
sobject_id |
string | GALAH observation identifier |
star_id |
string | GALAH unique star identifier |
tmass_id |
string | 2MASS identifier |
gaiadr3_source_id |
string | Gaia DR3 source identifier |
ra |
float64 | Right Ascension J2000 (degrees) |
dec |
float64 | Declination J2000 (degrees) |
teff_k |
float64 | Effective temperature (K) |
logg |
float64 | Surface gravity (log cm/s^2) |
fe_h_dex |
float64 | Iron abundance [Fe/H] (dex) |
vmic |
float64 | Microturbulence velocity (km/s) |
vsini |
float64 | Projected rotational velocity (km/s) |
radial_velocity_kms |
float64 | Barycentric radial velocity (km/s) |
radial_velocity_comp2_kms |
float64 | Binary companion RV (km/s) |
snr_px_ccd1..snr_px_ccd4 |
float64 | Signal-to-noise per pixel (4 CCDs) |
snr_mean |
float64 | Mean SNR across all 4 CCDs |
flag_sp |
Int64 | Spectroscopic quality flag (0 = best) |
flag_red |
Int64 | Reduction pipeline quality flag |
li_fe..eu_fe |
float64 | Elemental abundances [X/Fe] (dex) — 31 elements |
n_abundances |
Int64 | Count of non-null abundance measurements |
Abundance columns
Light: li_fe, c_fe, n_fe, o_fe ·
Odd-Z: na_fe, al_fe, k_fe ·
Alpha: mg_fe, si_fe, ca_fe, ti_fe ·
Iron-peak: sc_fe, v_fe, cr_fe, mn_fe, co_fe, ni_fe, cu_fe, zn_fe ·
s-process: rb_fe, sr_fe, y_fe, zr_fe, mo_fe, ba_fe, la_fe, ce_fe, nd_fe ·
r-process: ru_fe, sm_fe, eu_fe
Usage
from datasets import load_dataset
ds = load_dataset("juliensimon/galah-dr4-stellar-abundances", split="train")
df = ds.to_pandas()
# High-quality stars with best spectroscopic flags
best = df[df["flag_sp"] == 0]
# Metal-poor stars
metal_poor = df[df["fe_h_dex"] < -1.0]
# Stars rich in europium (r-process)
eu_rich = df[df["eu_fe"] > 0.5]
# Stars with the most measured abundances
well_measured = df.sort_values("n_abundances", ascending=False).head(1000)
# Kiel diagram (logg vs Teff)
import matplotlib.pyplot as plt
sample = df[df["flag_sp"] == 0].sample(50000)
plt.scatter(sample["teff_k"], sample["logg"], c=sample["fe_h_dex"],
s=0.1, cmap="coolwarm", vmin=-1.5, vmax=0.5)
plt.gca().invert_xaxis()
plt.gca().invert_yaxis()
plt.xlabel("Teff (K)")
plt.ylabel("log g")
plt.colorbar(label="[Fe/H]")
Data source
GALAH Survey DR4 (Buder et al. 2024). Observed with the HERMES spectrograph (R ≈ 28,000) on the 3.9m Anglo-Australian Telescope at Siding Spring Observatory.
Update schedule
Static dataset — uploaded once from the DR4 release catalog.
Related datasets
- gaia-dr3-astrophysical-parameters — Gaia DR3 stellar parameters
- exoplanet-catalog — Confirmed exoplanets
- pulsar-catalog — Pulsar catalog
Pipeline
Source code: juliensimon/space-datasets
Citation
@article{buder2024galah,
author = {Buder, Sven and others},
title = {The GALAH Survey: Data Release 4},
year = {2024},
journal = {arXiv preprint arXiv:2409.19858},
}